Abstract: It is an object of the invention to provide an economical milling cutter for T shaped groove.This invention is a milling cutter for T shaped groove comprising at least three cutting edge mounting seats distributed peripherally on a body one end flange of the milling cutter, on the first cutting edge mounting seat a first cutting edge for cutting remotest part from the cutting machine being mounted, on the second cutting edge mounting seat a second cutting edge for cutting nearest part from the cutting machine being mounted, on the third cutting edge mounting seat located between the first and second seats a third round or polygonal cutting edge being mounted, and the third cutting edge projecting radially outwardly from the rotation center line of the body between and from two portions cut by the first and second cutting edges.